nonidentity vs separateness

nonidentity and separateness both are nouns.

Word	Noun	Adjective	Verb	Adverb
nonidentity	Yes	No	No	No
separateness	Yes	No	No	No

As nouns, separateness is a hypernym of nonidentity; that is, separateness is a word with a broader meaning than nonidentity:

nonidentity: Difference, distinction; failure to be identical.
separateness: the quality of being not alike; being distinct or different from that otherwise experienced or known

Other hypernyms of nonidentity include distinctness, otherness.

nonidentity (noun)	separateness (noun)
Difference, distinction; failure to be identical.	the quality of being not alike; being distinct or different from that otherwise experienced or known
	political independence
	the state of being several and distinct